Letting Off Steam
by KaydenceRei
Summary: Typically when the Lullaby occurs, Bruce is left exhausted and drained. There's just one time where he's left with far too much energy and a whole lot of frustration, but fortunately, Natasha offers to help. [Originally a one-shot. Grand finale added, enjoy.]
1. Chapter 1

**Disclaimer** : I'm not even sure I own this overactive imagination, so no, nothing is mine.

 **Letting Off Steam** :

What usually occurred any time the Lullaby was put into effect on The Hulk was that Bruce would return to find himself exhausted and drained and he would be laying on the ground wherever Natasha performed it. At least that was how it worked the last dozen times.

Lullaby number thirteen turned out quite different. Sure, he came back to his senses in the middle of the woods wearing only his pants, as per usual, but he was by no means tired or drained. Bruce was something else entirely that he couldn't make heads or tails of in his post-Hulk haze and he was actually still on his feet.

"You alright?"

Her voice made him turn his head in Natasha's direction as he glanced over the dark red and endless waves of hair that went past her shoulders. She stood casually with her arms crossed a few feet away but those deep green eyes were studiously watching him with the barest semblance of concern. He wasn't entirely sure how to respond to the question and he glanced away and looked around.

"Bruce?"

This time the concern seeped a little into her voice and he turned his eyes back on her for a moment. "I need a few minutes," he told her.

Her brow ruffled just slightly before she shrugged, "Alright."

But she didn't go anywhere and he realized he forgot to emphasize on that, "Alone."

Natasha's face didn't change much as folded her arms across her chest, "What's going on, Bruce?"

"I'm just..." he sighed a little. _What was going on?_ What was going on was that he had enough energy to power a small town and that was putting it mildly. Bruce wasn't entirely sure how to explain that he was frustrated beyond belief at the moment and he just needed a few minutes to get it out. "Frustrated..."

She blinked a few times at that. "So hit a tree or something, let it out," and if it weren't for the way he was feeling right now, he might have actually laughed at that.

"It's not—not that kind," he groaned out in disbelief.

"Oh." He turned around fully and watched as she studied him with curiosity before one corner of her lips curled upwards into this slanted little smile, " _Oh_."

That did _not_ make things better.

Her eyes shifted from his face, to his chest and then lower before the other corner of her lips quirked up. Natasha gave him a rather coy look to go along with that ridiculous little smile, "You need a little help with that?"

There was no way she was making that offer with any sincerity and he groaned before shaking his head. "Just, please go somewhere else, Natasha?" he requested again.

Of course, Bruce has been proven wrong about many things with her many times, and this appeared to be one of those moments. Her head tilted to the side just slightly and he thought for a moment she was going to do as he asked. Instead she stepped forward and moved towards him and he froze a little when she tugged at the zipper at the front of her catsuit.

"W-what are you doing?"

"You need to let off some steam, Bruce," she purred as she stepped just in front of him. The zipper was pulled down enough to show ample amounts of skin and curves and he sucked in a breath.

"Natasha..." he warned gently. All that frustration made it near impossible to deny her when the invitation to have her was so clearly open and available. And unzipped.

Bruce blew out a breath as she took a step even closer, took his hand, and placed it on the zipper that rested halfway between her breasts and her navel. It was enough to take away the last of the will he still had left to send her away. He tugged the zipper further down and pressed his lips to her neck as his hands moved to push the uniform down off of her shoulders. He could feel her kicking off her boots and she pushed them away as he moved her back. His mouth trailed a path from her neck and up to her mouth until her back hit a nearby tree.

Natasha didn't seem at all fazed by the sudden halt in movement and he was left reeling as her lips devoured his own the moment her tongue snaked its way into the fold. She did seem a little surprised when he broke the liplock and left a trail of kisses from her mouth, down her jawline, until he finally reached her neck again. The tiniest noise escaped her, some mixture of a sigh and a moan, and it came as equal surprise to both himself and to her. It seemed to Bruce that he had hit the right spot and he moved his lips back over it until the noise emitted from her lips again.

Her hands pressed against his chest, fingertips leaving a small trail down and he groaned a little at the contact. She was wriggling the suit the rest of the way down until she kicked that aside as well and he worked his hands around her bra as she tugged at his worn out pants. He tossed the bra into the growing pile of her uniform and boots, pressing his hands against the breasts that had been revealed beneath them and she writhed a little when he moved his mouth lower and gave attention to each.

Bruce licked and teased until Natasha finally gave him a small but forceful push away. For a moment he thought she was changing her mind until she spoke again, "Pants." One word, spoken in a rather raspy tone, but he understood the meaning. She shoved them the rest of the way down and he kicked them into the pile of her own gear, finally getting a decent view of her in her entirety. It wasn't as though he had never noticed how tiny Natasha was before now, but her lithe frame was certainly a sight to behold in it's unclothed splendor. Before he could continue to soak in the view, she pulled him back to her and ravaged his mouth once again.

It seemed like a horrible thing to use her to release the tension and frustration left behind from his transformation, but she didn't seem to have a single problem with it, and he figured he probably shouldn't either. It wasn't as though she wasn't enjoying it, if the small noises she released on occasion were any indication, and he pressed his hands over her breasts as he pushed her back against the tree.

"Enough, Bruce..." she murmured against his neck.

He watched as she shimmied from her panties as the last barrier stopping them was shoved aside. She proved her point when she reached down and took him in her hand. That was the end of the line for him. Bruce shifted his hands around her until they cupped her bottom and he lifted her up and onto him. Her thighs locked around his waist and he saw her eyes flutter shut while her lips parted a little before she bit a moan into his shoulder.

He moved in an instant with no set pace, but it was faster and rougher than he meant to be and he could feel Natasha's hands move around to his back as she held on. Her fingernails dug into his back in an instant, leaving a ridiculously pleasurable and painful sensation. He had a feeling she was leaving marks, but he wasn't going to complain about that, not after this.

He thought he heard his name in the next throaty little moan but he couldn't really be certain. Bruce pressed his lips against the pulse line on her neck, trying and failing to slow his pace so that she could keep up. Natasha was making an effort to meet his thrusts but he knew that given her position, it wasn't an easy feat and he was a little impressed with what she was managing. She slung one arm around his neck and he had a feeling she was quite literally just hanging on for the ride at this point.

Her breaths came out in little pants as she nipped at his shoulder until one of his thrusts seem to hit the right spot. She gasped a little and he made note of it, moving faster and angling for that same spot. The tiny gasps became more than that, strangled little noises that she was trying not to release because _control_ was everything to her, and she seemed to be losing her grasp on it at this very moment. Admittedly, he was a little proud of that.

Her nails clawed their way into his back again as he pushed into her faster until she just seemed to let it all go. Natasha's body trembled with the latest one and he paused for a moment as she shuttered and caught her breath.

"Shit..." she murmured out as she rested a rather sweaty forehead against his own, "And you're still...?"

Bruce gave her a rather meager nod at that. He put her down on shaky feet and he couldn't hide his surprise when she shoved him onto the ground on his back.

"We're not done," she informed him with that raspy voice.

Natasha didn't give him a chance to disagree before she knelt over him and sank onto him. Her eyes glazed just slightly, likely still reeling from her release just moments ago as she took him in entirely. There was only a small moment where she took another breath, pressed one hand to against chest, and bucked her hips with such speed that made him groan in pleasure. He settled his hands on her waist as she moved without any particular pattern and she only slowed down when he got a hand into her hair and pulled her mouth down to his.

He could feel her trembling already, slowing down to delay her own pleasure and obviously to extend his. Bruce didn't think that was necessary as their tongues collided and he moved faster where she had slowed down. She gasped into his mouth and again he felt her nails, though this time it was as they dug into his chest.

Natasha was clearly trying to mutter out words to slow him down, but instead he moved a little faster until she crumbled again, this time though, he came with her. He blew out shaky breaths as she remained on top of him, her cheek pressed against his shoulder as she panted a little against his skin. She stayed there for a while not moving or speaking, and he wasn't all that sure what to say, even if he thought he could find the will to release some words.

Finally she rolled off him, her back landing rather haphazardly on the ground beside him, resting on the same leafs and twigs that he rested on. "Better?" she finally questioned, her voice a little bit more in control than the last times she had spoken.

Bruce nodded numbly at that as he turned his head to peer over at her, "You have no idea..."

There was a sultry little chuckle she blew out before she spoke again, "I have _some_ idea." And he supposed that was definitely true. "Think that'll happen again?" she asked next.

"Uh..." and all he could think was how embarrassing that would be. This was embarrassing enough now and he covered his face with his hands to hide the flush of his cheeks.

"Well, if it does then I certainly won't complain."Bruce peered through the cracks of his fingers at the saucy little smile she gave him and she looked... satisfied. There was no mask on, no hidden emotions, nothing but a rather satiated Natasha Romanoff as her green eyes stared into his own brown ones. He huffed out a tiny little laugh before he moved his hands and she grinned, "Don't get weird about this, Bruce."

"I'll try," he told her. And he really would, but it would be near impossible to look at her the same way again, not after seeing her naked and completely unmasked. He blew out another breath before he asked the most important question, "How long before anyone starts to wonder about where we are?"

"Probably too late for that," Natasha offered up with a sweaty shrug, "Give me two more minutes to get the feeling back in my legs and I'll come up with something legitimate."

Bruce nodded and smiled a little at that, "Alright..."

"Good luck explaining the scratches on your back though."

He groaned at that, but it was hard to be even a little upset when Natasha released a tiny little laugh in response, and instead he just smiled a little and pulled a leaf out of her hair.

* * *

 **Hope you enjoyed. Mature writing is not my expertise.**


	2. Chapter 2

Of course, there was never _meant_ to be a second chapter, but why the hell not, right? I know it's been almost a year and a half since I posted the original one-shot, but hey, when it comes to smut, there's just no such thing as 'too long'. Pun intended of course, courtesy of **Black' Victor Cachat**. xD

 **Chapter 2** :

Natasha was still half asleep when the rather loud knock at her apartment door inside the tower had her reaching for her gun. It was impulse, not that she actually believed she needed the weapon, but she took it from under her pillow nonetheless. She swiveled on the bed, planted her bare feet on the carpet, and padded her way silently into the living room, and the main door.

She had to admit she was only completely alert and aware for the two minutes it took her to answer the door, not bothering to hide the gun in her hand as she did so, but also not bothering to look beforehand at who might be on the opposite side. If it was Tony, he certainly deserved to piss his pants a little for waking her up at three in the morning.

Once she opened it and saw Bruce, her mind went back to half-asleep mode, and she placed the gun down on the small table, just beside the door. His eyes only studied the gun for a fraction of a second but he certainly didn't seem surprised by the sight of it, in fact, he almost looked—enticed?

"Bruce," she greeted in a half-murmur, barely stifling the yawn as she stretched her arms a little. He had never knocked on her door before, their private abodes being a threshold neither had ever dared to cross, until right now.

Natasha didn't bother with any more of a verbal greeting, she merely left the door open for him and turned around, heading back inside.

"Natasha."

She turned at the odd edge his voice held, studying him more carefully now. He hadn't moved from the doorway and she tilted her head to the side slightly, forcing her brain out of the muddle of sleep it was stuck in. "You okay?" she questioned.

Bruce just looked like a giant bundle of frayed nerves, his foot digging into the carpet of the doorway awkwardly. Finally he spoke again, "You remember a few months ago...?"

And she most certainly did. "Quite well," she assured him with a smirk.

"And you asked if...something like that might happen again?"

"I did..." Natasha agreed, then she narrowed her eyes a little before sleep completely left her brain, then the lightbulb went a little brighter in it's stead. She felt herself voicing the exact same single word that she had the previous time a few months prior, " _Oh_..."

He looked like he had absolutely no idea what to do, if he should step further inside, or if he should run for the high hills and forget what he came here for.

She couldn't help the throaty little chuckle that came from her lips in reaction before she spoke again, "I told you not to get weird about this, Bruce." She crooked her finger at him in a come hither gesture, "I also told you I wouldn't complain if something like that happened again, though next time...at least have the good manners to de-Hulk at a more decent hour."

The poor scientist was wide-eyed, stunned at her easy acceptance of the his sudden appearance and need, and to be frank Natasha was a little surprised by it herself. He wasn't the first person to give her release, not at all, but he _was_ the first person to take away that control she held so dearly before she was sure she was ready to do so—and he was definitely the first to do it _twice_ in a row, and in an equally short period of time.

Natasha couldn't quite deny she had been hoping it might happen again, though she wasn't entirely sure she wanted it to happen again in her quarters. She swore, it was like she was trying to set up rules to a dangerous game while she was already far too deep into playing it. She sighed as she folded her arms and perched herself against the end table by her bookshelves, shelves that held stupid baubles that Clint had continued to get her over the years. He seemed to think it was funny. A little Buddha statue here. A couple snow globes there. All stupid things that she just kept putting on her bookshelf with her books.

In hindsight, she probably should have picked a better place to question the wisdom of their dalliance in her semi-apartment.

Bruce finally dared to enter and close the door behind him. He didn't lock it, though she didn't imagine anyone in their right mind would enter without her express permission, not without a rightly earned fear of bodily harm or death anyways.

The idea that she shouldn't allow him to take her control in one of her few safe spaces completely went out the window when she saw that hunger, that darkness, clouding his eyes. No, instead her body betrayed her instincts, and she felt that warmth sinking lower as she bit down on the inside of her lower lip, anticipation giving way to her uncertainty.

He was up against her now, his body flush against hers. Natasha exhaled as he backed her fully into that ridiculous little end table. It was probably a good thing Stark spared no expense, she doubted a discount store end table would hold up against what was so clearly about to happen to it. That was when she realized she wasn't really wearing a whole lot to begin with—a pathetic little tank top and a pair of black shorts, nothing else. It was no wonder he was so quick to move on her.

Bruce's hand was on her waist, his fingertips were curled around the hem of her tank top, and for a good minute, all they were doing was breathing. He was staring straight into her eyes, and Natasha nearly lost it then and there, because with the way he was looking at her now—it was like he wanted dessert, and she was at the top of the menu.

It felt like he was teasing her in that moment, staring her down like she was something to devour and yet doing absolutely nothing, nothing sans for pooling that heat and need lower, and lower, until it couldn't possibly go any further. She had to admit she was surprised by the shaky little breath she released in that moment, though it did seem to coerce him into finally doing something else, and he did it with a little smirk that was remarkably enticing.

Bruce waited just long enough, then his other hand cupped her jawline, his thumb slowly making an unforgettable little path of circles over her cheek, persuading her lips to part just slightly. And then, the dorky scientist didn't just kiss her; no, he took her mouth, he practically ravaged it. He claimed it and she gave it over to him fully. She pushed her hips forward, pressing against him almost as though she were drawn in like a magnet, and she supposed she sort of was.

Natasha would damned, but she had a feeling any time Bruce looked at her the way he had just done, then in the future she might just rip her clothes off herself and let him help himself. The control he took from her while attempting to get back a semblance of his own was absolutely breathtaking and tantalizing.

And the sound she made deep in the back of her throat when she felt him through her clothes, it seemed to drive him absolutely mad. He pushed back against her further in that moment, just enough that her back roughly pushed against the table, which tapped against the wall, and the bookshelf beside it shook just a little. The rattling of books and baubles on it only made her a bit more ravenous than he had already made her himself.

Bruce kept his lips on her own, pushing her shorts down until they hit the floor below her feet. The little table was digging into her lower back and she finally pulled away, then used her hands to lift herself onto it. She lifted one leg, and then with his help, the other leg too, and she rested her calves on his shoulders as she leaned back and let him find the right angle. His own pants were gone already, and she tried not to hold her breath as he entered her. It was either hold it all in or shout loud enough that Jarvis would probably send for help. She was stuck in between, her breath coming in, and puffing back out in short bursts. Her hands gripped the shelf, her knuckles going white until he was all the way in, and then she reached out to grab the front of his shirt with a tight-fisted grip.

Natasha had to admit, she probably wasn't as ready for that as she should have been, especially considering she had prompted him to do it, and the words came from her mouth a little unbidden, suddenly wondering if she could really handle jumping right this madness, "Fuck..."

The poor scientist was wary for a moment, more patient than any man she had ever seen who had just entered a woman. He seemed to be fully aware of just how tight she was in that moment, and his one hand rested on her knees when she felt his other hand press to that bundle of nerves. She felt her eyes glaze a little when he rubbed a little circle, enough so that she hardly noticed when he withdrew from inside her the tiniest bit, gauging her reaction when he pushed back in ever-so-slightly.

It was just the right mix of pleasure and pain. The guttural little moan she emitted, along with the absence of a no, was a fairly good indicator that it was okay. But he was still hesitating, so she clutched his shirt and the bookshelf a little tighter, then she gave him a slight nod. It seemed to be all the affirmation he needed as he thrust hard into her. The books and baubles rattled on the shelf, covering only part of her sharp cry. Then Bruce thrust again, even harder, and the Buddha statue fell off the shelf and banged on the floor. Natasha moaned, and it seemed to be enough to show him she could handle what her bookshelf clearly couldn't.

It was an almost perfect rhythm as Bruce thrust into her again, and again. The books on the shelf crept closer and closer to the edge until they ran out of flat surface and fell over, taking one of the snow globes with them in their tumble. It shattered, not that Natasha was entirely sure she cared in that moment, the water and fake snow splattering to the side of them.

A few more books thudded around on the shelf, a jeweled dagger shook on it's little display stand, and other stupid decorations thudded as her hand clutched to the shelf tightly. Bruce's eyes were looking right into hers, and they both listened to the rhythm of all the noises they were creating in melody with their moans.

He daringly leaned closer, pushing her thighs closer to her chest, and Natasha felt her jaw nearly drop at the sensation. Her knees were bent over his shoulders now, he wrapped his hands tight around her taut thighs. Her cries matched his thrusts, and they rang in perfect harmony with the sounds of the clanging on the shelf, as he quite literally screwed her senseless. One of his hands went back to that already throbbing bundle of nerves and Natasha released his shirt, instead wrapping that arm around the back of his neck.

It seemed he remembered the best spot to hit too, because he found it again, and he was practically taunting it inside of her. She was going to lose all sense of the word control any moment now. And he started going faster.

"Oh, God..." Natasha whispered, high pitched and desperate, and two words she never thought she might hear herself utter. Down came the jeweled dagger, a set of butterfly knives, and a few more books.

The wall shook, a painting clattered down to the floor, and Natasha's pleasure pushed her higher and higher until the ultimate feeling hit her, and she couldn't see what was in front of her anymore. Her eyes were squeezed shut so tight her vision was white, little gold dots floating across it. Compared to the silence she originally intended to maintain, Natasha was _loud_ when she came, and she knew Bruce could tell she actually _was_ stifling the sounds she was making despite how loud it still came out. That was impressive enough because she knew full well, even as much as she quieted herself for that, it still wasn't quiet at all.

Bruce pressed closer, thrusting faster, and Natasha unintentionally pulled on his neck until their foreheads were touching. She could barely breathe, and as her climax began to fade into his, she pressed their lips together. The entire book shelf was teetering and Bruce grunted, much quieter than Natasha herself had, and soon after that it was over. She could tell by the way everything slowly stopped shaking that it was almost at the end, and she realized that with a bit of sadness, wondering when the next opportunity would present itself.

He pulled out, moving back just enough to let Natasha take her legs off his shoulders, though she wasn't entirely sure they would be steady enough to get off that overly tiny end table just yet.

She groaned a little as she felt the tightness in her legs, fully feeling the effect of so tightly winding up her muscles in her back and legs, but Bruce stayed close, halting her before she could lower her feet to the ground. He eased her to face the opposite side of the bookshelf and _then_ she remembered the shattered snow globe, chuckling a little as she made it to a safe portion of the floor.

And Bruce was staring at her now, almost like he suddenly couldn't believe they had just done this. _Again_. To be frank, Natasha was just as surprised by it as he was.

"I just..." he cleared his throat before he spoke again, voice still edging on the borderline of satisfaction and a little bit of guilt, "I know I needed that but...thank you."

"You really are a dork, Bruce," she informed him, smiling softly as she rolled her eyes. He was awkwardly averting his eyes now, holding her shorts out to her in the most endearingly polite way, as if he hadn't just properly ravaged her in every possible way.

Her fingertips brushed his as she accepted the shorts from him, and Bruce finally dared to look at her again, meeting her gaze in one of the most mind blowing ways possible. He just looked absolutely vulnerable, and though she also knew that she was equally as unmasked just then, she doubted she looked 'vulnerable', but she was certain she at least looked like a hot mess.

She never imagined Bruce Banner might be her undoing.

"I uh...I think we might be doing all of this a little ass backwards," Bruce finally mentioned.

"Doing all of...what, exactly?" she dared to ask him, her brow wrinkling as she tried to decipher his comment.

Bruce looked a little uncertain now, awkwardly so, and she was almost entranced by how endearing she found him when he looked like that. "The uh—the part where we settle down somewhere first, have wild sex second, then have a romantic little locking of the eyes last..." he mumbled out.

Natasha laughed softly, she couldn't help it, mostly because he was just so right. She raised her hand up, pressing it softly to the side of his face, and she would be damned if she didn't go just a little fuzzy when he smiled sheepishly at her. He looked absolutely entranced, a soft and warm look in his eyes before he pressed close to her, taking her face in his hands and kissing her. It seemed he wasn't ready to let the moment go, and her mind reluctantly agreed. She accepted the kiss, she even kissed him back, long and slow.

She sighed into the kiss, which was even more surprising to her, enjoying the softness of his mouth on hers.

Bruce seemed to think the noise meant the opposite, stepping back and glancing down at the floor almost shamefully.

Common sense told her he was going to make an escape, and her own words, even joking, surprised her most of all, "Do you want to run off now, or are you going to take me to bed?"

"I..." and Bruce's mouth was open just slightly, almost as though he didn't quite believe what he had just heard.

Natasha could see his internal struggle, and she knew it was because he felt like he was using her, and she appreciated the honesty his eyes were giving her in that moment. She wouldn't be bothered if it turned out it was all he wanted from her, but she figured she also wouldn't be bothered if it turned out he wanted just a little bit more than to use her.

There was only one way she would find out, and that was by asking what she did next. "Will you stay?" she asked him, her voice soft and welcoming now.

He seemed to relax much more now, like he was relieved she had actually asked and not just joked about it. He reached up, tucking a stray strand of hair back behind her ear as he finally asked his own question, "Guess you're as lonely as I am?"

She mulled the words over in her head before she smiled, tugging her shorts on before sauntering down the hallway towards her bedroom, ignoring the disaster they had created in her living room.

"Not so much anymore," she called back, not looking to see if he followed.

But he did. She could hear his footsteps as she walked the path to her bed.

* * *

 **Well, originally I intended to write this as part of Art of Persuasion, but unfortunately it didn't at all fit in to the way that story is going to go. I did realize it would fit perfectly as a second part towards this one though, so this is where it went after a few edits to seal it in as a follow-up piece.**


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